The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories

Exoplanet research has moved from the discovery of new classes of planets toward creating a census of exoplanet population demographics across the spectrum of exoplanet and host star masses. This census will constrain possible exoplanet formation and evolution theories. Direct imaging and ground-bas...

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Main Author: Alan P. Boss
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adb728
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author Alan P. Boss
author_facet Alan P. Boss
author_sort Alan P. Boss
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description Exoplanet research has moved from the discovery of new classes of planets toward creating a census of exoplanet population demographics across the spectrum of exoplanet and host star masses. This census will constrain possible exoplanet formation and evolution theories. Direct imaging and ground-based microlensing surveys excel at detecting long-period exoplanets. The Roman Space Telescope microlensing survey (RMS) will help complete the census by possibly discovering hundreds of long-period and free-floating exoplanets. Long-period gas giants are difficult to form by the classic core-accretion mechanism, whereas the gas disk gravitational instability (GDGI) mechanism can form gas giants at distances of 10 au and beyond for AFGKM host stars. The Enzo 2.6 adaptive mesh refinement three-dimensional hydrodynamics code is used to model the formation of gas giant protoplanets by GDGI around solar-mass protostars, for future comparison with the RMS, which will provide convincing evidence about whether GDGI is needed to explain exoplanet demographics. Previous Enzo models have shown that a robust GDGI is able to form enough gas giants in a single system to result in the ejection of a significant fraction within ∼2000 yr, a likely source of free-floating exoplanets. The present models investigate the GDGI outcomes for a larger range of initial protoplanetary disk masses and outer disk temperatures than in the previous work of A. P. Boss, resulting in the formation of abundant substellar companions with masses in the range of ∼0.1 to ∼100 M _Jup on orbits ranging from ∼3 to ∼30 au.
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spelling doaj-art-746ca4c5e3004174bd0d6afb7ef5b4412025-08-20T02:56:44ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198211710.3847/1538-4357/adb728The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation TheoriesAlan P. Boss0https://orcid.org/0000-0001-7119-1105Earth & Planets Laboratory , Carnegie Science, 5241 Broad Branch Road, NW, Washington, DC 20015-1305, USA ; aboss@carnegiescience.eduExoplanet research has moved from the discovery of new classes of planets toward creating a census of exoplanet population demographics across the spectrum of exoplanet and host star masses. This census will constrain possible exoplanet formation and evolution theories. Direct imaging and ground-based microlensing surveys excel at detecting long-period exoplanets. The Roman Space Telescope microlensing survey (RMS) will help complete the census by possibly discovering hundreds of long-period and free-floating exoplanets. Long-period gas giants are difficult to form by the classic core-accretion mechanism, whereas the gas disk gravitational instability (GDGI) mechanism can form gas giants at distances of 10 au and beyond for AFGKM host stars. The Enzo 2.6 adaptive mesh refinement three-dimensional hydrodynamics code is used to model the formation of gas giant protoplanets by GDGI around solar-mass protostars, for future comparison with the RMS, which will provide convincing evidence about whether GDGI is needed to explain exoplanet demographics. Previous Enzo models have shown that a robust GDGI is able to form enough gas giants in a single system to result in the ejection of a significant fraction within ∼2000 yr, a likely source of free-floating exoplanets. The present models investigate the GDGI outcomes for a larger range of initial protoplanetary disk masses and outer disk temperatures than in the previous work of A. P. Boss, resulting in the formation of abundant substellar companions with masses in the range of ∼0.1 to ∼100 M _Jup on orbits ranging from ∼3 to ∼30 au.https://doi.org/10.3847/1538-4357/adb728Exoplanet formationExtrasolar gaseous giant planetsGravitational instabilityAstrometric exoplanet detection
spellingShingle Alan P. Boss
The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
The Astrophysical Journal
Exoplanet formation
Extrasolar gaseous giant planets
Gravitational instability
Astrometric exoplanet detection
title The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
title_full The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
title_fullStr The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
title_full_unstemmed The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
title_short The Roman Microlensing Survey: Confirmation or Refutation of Gas Giant Exoplanet Formation Theories
title_sort roman microlensing survey confirmation or refutation of gas giant exoplanet formation theories
topic Exoplanet formation
Extrasolar gaseous giant planets
Gravitational instability
Astrometric exoplanet detection
url https://doi.org/10.3847/1538-4357/adb728
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